Unearthing a Colored Past: The Challenge of Qin Dynasty Pigments

When the first fragments of the Terracotta Army emerged from Xi’an’s soil in 1974, archaeologists faced an unexpected dilemma: traces of vibrant pigments clinging stubbornly to the clay. These 2,200-year-old statues weren’t the monochromatic figures we see today—they were originally painted in striking reds, purples, and blacks, a polychrome army meant to accompany China’s first emperor into the afterlife. The real excavation challenge wasn’t extracting the warriors from the earth, but preserving the millimeters-thin paint that had survived two millennia underground.

Surgical Precision in Archaeological Conservation

The conservation team’s toolkit reads like a hospital inventory: cotton swabs, medical gauze, plaster casts, and an array of surgical blades. Circular, curved, and triangular scalpels—each selected for specific tasks. The 12-blade scalpel handles thick soil layers for deep cutting, while the 20-blade tackles delicate surface work. Archaeologists even adopted surgical techniques, training with diagrams of proper blade grips—the pen-hold for delicate strokes, the palm grip for controlled pressure, and the reverse-pick for upward precision cuts.

“Think of it like a chicken pecking rice,” veteran conservators would demonstrate. “Too much force, and the grain shatters.” The angle of the blade proves critical—gradually flattening as it nears the pigment layer. When stubborn patches resist the tip, the blade’s edge performs a careful scraping ballet.

The Hidden Labor Behind Museum Glass

April 2, 2010, in Pit No. 1’s tenth corridor: four archaeologists kneel for hours around Warrior No. 24, its white foot surfaces still bearing orange-red laces and purple trouser hems. The clock ticks toward the 5 PM deadline—all conservation must pause for the weekend. As knees ache against cold concrete (until thoughtful students provide foam “kneeling pads” nicknamed “Xiao Yanzi’s comfort,” after a popular Qing Dynasty drama character), tourist murmurs float over the barriers: “They work so slowly—days to uncover one piece.”

The real adversaries prove less visible: pit conditions mimicking a clinical environment gone awry. Summer turns the enclosed space into a humid oven; winter brings bone-chilling dampness. Climate control devices are forbidden—fans risk flaking pigments, heaters cause micro-fractures. Team kits stockpile not just tools but menthol patches, dampness-relief pills, and anti-inflammatory ointments.

The Science of Saving Colors

Preservation begins with humidity calibration—a misting ritual as precise as a laboratory procedure. Using spray bottles held 10–15 cm above the surface, conservators achieve exactly 83.5% relative humidity and 18.7% water content in the soil. The 12-sickle scalpel then advances in 3 mm increments, followed by rehydration cycles.

Here, terminology matters: these are “pigment traces” (yíhén), not artifacts (yíwù). While weapons and pottery can be moved, the paint exists in limbo—part of the object yet separate. Over-spraying makes pigments swell and detach; under-spraying leaves soil too hard, causing colors to stick to displaced dirt. The balance demands intuition honed through years—knowing when subsurface soil should remain “firm-firm” (硬硬儿的) while surface layers turn “muddy-soft.”

When Public Perception Clashes With Conservation

December 22, 2019: social media erupts over images of archaeologists “watering” the Terracotta Army. Outraged posts accuse the team of damaging relics, unaware that dehydration causes pigments to curl and vanish within minutes. The conservation team, caught between viral misinformation and bureaucratic requests for “brief explanations,” struggles to convey nuances:

– Why distilled water? Minerals in tap water cause crystallization.
– How much moisture? 18–19% soil saturation—measured by weight.
– The “steeping time” paradox: surfaces need softening while lower layers stay firm.

As one veteran quipped, translating tactile experience into reports is like “explaining calligraphy to someone who’s never held a brush.”

Layered Complexity: The Warrior’s True Colors

Cross-sections reveal the paint’s sandwich structure: a base of raw lacquer (still sticky after centuries), topped by single or double pigment layers. Each demands unique approaches:

– Armor grooves require “dotting” with damp swabs
– Smooth sleeve surfaces need 20-blade scalpels at 15-degree angles
– Curved areas demand crescent-shaped blades with a final “gliding” motion

Post-cleaning, warriors receive a PEG (polyethylene glycol) “moisturizing treatment”—the same compound found in skincare products—before being swaddled in medical cotton and cling film. The team’s dark humor shines through as they tuck in the statues: “Blankets for the Grandpa,” referencing local farmers’ initial term for the figures—”Clay Gods” (瓦神爷).

Legacy in Every Stroke

Beyond technical mastery, the warriors’ conservation represents a philosophical shift. Where early archaeology prioritized extraction, modern practice embraces micro-scale preservation—each pigment fleck a data point in understanding Qin Dynasty chemistry, trade networks, and artistic conventions. The true achievement isn’t just saving colors, but redefining how we value impermanence in the archaeological record. As lasers now map pigment distributions and nano-materials promise enhanced consolidation, the humble surgical blade remains the conservator’s most trusted ally—a bridge between ancient craftsmanship and contemporary science.

The next time you see a Terracotta Warrior, remember: its muted hue isn’t absence, but a testament to the fragile, colorful history still being carefully uncovered—one grain of soil at a time.